Dot Gain

[helmuttgutenberg]

Hi Gordo,

We have printed a test file and tried to cakibrate out Kodak Thermal CtP according to ISO 12647-2 for paper type 1 gloss and , printed the imeg with 60-70 and 80 lpc dots and looked at the ISO 12647 documents for TVI values, it says for 54- 70 lpc dot how about 80 lpcm dot any standarts?

[Lukas Engqvist]

I think the more practical approach is to deviate from ISO and ignore the lpc definitions. Customers will not want to have a different version of 50% grey at any LPI. The problem is that the ISO was defined as "this is what you get with a linear film".

Since most customer proofs, and separations will assume a FOGRA 39 on a type 1 paper your customers are most likeley to expect TVI value of 17 @ 50% for K (curve B) and 14% for CMY (Curve A) at any LPI. This is how the standard ought to have been defined if it is to gain status as "standard". As far as I know this is the defacto way of implementing it, even though "strictly speaking" it is breaking it.

For uncoated (type 3) the defacto curves are B for CMY and curve C (20 @ 50%) for K
For type 4 and 5 defacto curve C for CMY and curve D (22@ 50%) for K